“We no longer have that concern that they have this pawn they can then play against us,” said Mattis, former chief of U.S. Central Command. “So there‘s also a military vulnerability that the Haqqanis now face, that Taliban now faces because they no longer hold one of our U.S. soldiers in captivity. So, there’s also a freedom to operate against them that perhaps we didn’t fully enjoy so long as they held Bowe as a prisoner.”

Bergdahl was released at the end of May in exchange for five Taliban leaders who were transferred from the U.S. prison in Guantanamo Bay, Cuba, to Qatar, where authorities are supposed to monitor them for a year.

Critics of the prisoner exchange claim that the Taliban got the better end of the deal. Appearing with Mattis on Sunday’s show, retired Army Lt. Gen. William Boykin called the released detainees “five of the worst Taliban leaders in Guantanamo, two of which are mass murderers,” who now pose a threat to both Americans and Afghans.

“They were the senior commanders in the Taliban that had been captured and taken to Guantanamo,” said Boykin, the former chief of U.S. Army Special Operations Command. “These are bad actors and the Qataris can’t do anything to hold these guys in Qatar. They’ve even said they’re not going to monitor them. They’ll be back on the battlefield and they’re dangerous people.”

But Mattis countered that U.S. troops can make sure the released Taliban leaders don’t live too long if they return to the fight.

“If they were real men, they would have gone down fighting,” he said. “So, they’re not that tough. ... And we are quite capable, the ferocity and the skill of our troops when we close in on an enemy, these guys will not be that difficult to take out.”

While his son was in enemy hands, Bergdahl’s father grew a long beard as part of his efforts to understand Pashto culture, prompting critics in the U.S. to accuse him of trying to look like a Taliban fighter. Mattis said such attacks are unfounded.

“I think most of us got over judging people by the length of their hair by about 1975 in this country,” Mattis said.

Bergdahl’s parents have received death threats that are being investigated by authorities, but Mattis argued that they deserve understanding instead, noting that for five years they had been living in constant dread of the knock on the door informing them that the Taliban had murdered their son.

“You can imagine what it’s like to have gone through something like this for them, and I think a certain amount of compassion is appropriate for a family that’s been through this,” Mattis said.